Centrifugal compressors are well known in the industry as a source of compressed air for forced induction of air into an internal combustion engine. Their simplicity of construction and high efficiencies make them desirable as air pumps for these applications. Generally, they are powered by an exhaust gas turbine in a configuration very commonly known as turbochargers. Slow acceleration of these turbines known as “turbo lag” has always been an issue as turbine devices, although capable of large power output at very high speed, are low torque output devices on relative scale to positive as “turbo lag” has always been an issue as turbine devices although capable of large power output at very high speed are low torque output devices on relative scale to positive displacement devices such as gear, gerotor, vane or piston hydraulic motors.
Several patents relate to turbine type hydraulic devices to accelerate the turbo rotating assembly. Examples are:
U.S. Pat. No. 5,113,658 to R. Kobayashi describes a hydraulic assist turbocharger system operative to supply charge air to a combustion engine. The system includes at least one turbocharger having a hydraulic assist turbine adapted to be driven by a pressurized hydraulic fluid to supplementally drive the turbocharger during selected engine operating conditions when supplemental charge air is required. Hydraulic fluid flow is regulated by an electrohydraulic control valve responsive to control signals from a main controller, wherein the control signals and corresponding control valve operation may be independent of engine speed and load. In addition, the hydraulic fluid is supplied to the hydraulic assist turbine via a dual segment nozzle, with selector valves coupling the fluid for passage through one or both nozzle segments in accordance with engine charge air requirements.
U.S. Pat. No. 4,083,188 to E. Kumm describes a system for supercharging a low compression Diesel engine. The system includes connected turbine and compressor elements and a hydraulic system having a first motor/pump unit mechanically connected with the turbine and compressor elements and a second motor/pump unit mechanically connected, through an output transmission, to an engine. The hydraulic system also includes a plurality of valves, an accumulator, a reservoir, and ducts connecting such elements and the motor/pump units. The first motor/pump unit is of the variable volume type and is controlled by an actuator responsive to fluid pressures in the inlet and exhaust manifolds of the engine. The second motor/pump unit is a fixed displacement device which may be driven by fluid pressure from the accumulator in the engine starting phase and by the engine to supply hydraulic pressure to recharge the accumulator and assist in controlling the operation of the supercharger. The operation of the supercharger is also controlled in part by a valve mechanism responsive to fluid pressures generated by the motor/pump units during predetermined phases of engine operation.
U.S. Pat. No. 3,389,554 to G. Wolf describes a supercharged internal combustion piston engine having at least one exhaust-driven turbo compressor for supplying combustion air to the engine. The turbo compressor is provided with an auxiliary drive for supplying additional power thereto, the auxiliary drive comprising a hydraulic volumetric motor unit coupled directly to the turbo compressor, and a power driven pump unit connected by appropriate hydraulic conduits to the hydraulic motor unit and to a reservoir for hydraulic fluid. The hydraulic conduit leading to the hydraulic motor unit is connected to a source of air by means of an air conduit. The air conduit is provided with a normally closed pressure actuated valve whish is adapted to open when the pressure on the pressure-responsive actuating mechanism of the valve reaches a predetermined value. When the pressure actuated valve is thus opened, air or a mixture of air and hydraulic fluid flows through the motor unit.
U.S. Pat. No. 3,869,866 to S. Timoney describes drives and controls for an exhaust gas turbocharger for an internal combustion engine in which the turbocharger is primarily driven by exhaust gases from the engine and includes an auxiliary hydraulic turbine which also has a driving connection to the turbocharger and which receives pressurized fluid from a fixed displacement pump to drive the turbine during certain operating conditions of the engine. The pump is connected to a rotary output shaft of the engine by means of a clutch member which selectively connects and disconnects the pump in response to a preselected operating characteristic of the engine. Such operating characteristic is selected from the group consisting of at least one of the engine speed, oil pressure, air manifold pressure, and fueling rate characteristics of the engine. In one embodiment, the clutch is disconnected after the engine reaches a predetermined operating speed, as measured by a sensing unit or tachometer responsive directly to engine shaft speed, by sensing the pressure at which the fluid is discharged from the pump and which corresponds to the preselected engine speed. In another embodiment, the clutch control is also responsive to one of the operating characteristics of the engine for automatically disengaging the clutch in response to load conditions below a selected predetermined minimum, for example when the engine fuel depend rate is below 80 percent of the demand rate for maximum torque at a particular speed.
U.S. Pat. No. 3,927,530 to A. Braun describes a supercharged internal combustion engine having an exhaust-driven turbocharger for supplying combustion air to the engine and auxiliary power means for additionally applying a driving force to the compressor under occasional and otherwise normally deficient combustion air conditions, to provide the desired amount of combustion air for proper combustion. The power means includes a hydraulic assist motor mechanically coupled with the turbocharger and a hydraulic pump connected by a fluid flow passageway with the motor and permanently coupled with a drive shaft of the engine. The pump is connected through a selector valve to the oil in the reservoir of the engine's crankcase or to the vapor chamber above the oil level in the reservoir or to the atmosphere. The selector valve may be manually controlled or automatically controlled by a sensor responsive to one or more of such engine conditions as manifold air pressure, engine speed, etc. The valve may also have a bleed passageway therein that connects with the oil reservoir when the pump is pumping vapor or air to assure adequate lubrication of the pump and, if need be, the hydraulic motor.
U.S. Pat. No. 7,490,594 B2 to E. Dyne et al. describes a device combining the features of a supercharger, a turbocharger and turbo-compounding into one system, utilizing a hydraulic or mechanical continuously variable transmission to drive the turbocharger up to a specific speed or intake manifold pressure and then holding the ideal speed to keep it at the right boost pressure for the engine condition. The benefits of a supercharger, which is primarily good for high torque at low speed, and a turbocharger, which is usually only good for high horsepower at high speeds are merged. Once the exhaust energy begins to provide more work than it takes to drive the intake compressor, the device recovers that excess energy and uses it to add torque to the crankshaft. As a result, the device provides the benefits of low speed with high torque and the added value of high speed with higher horsepower or better fuel economy from a single system.
These forgoing known hydraulic turbines create more torque than an equivalent gas driven turbine as the density of the oil is roughly 1000 times greater than air, but still are relatively poor at creating angular acceleration. Positive displacement hydraulic devices create torque in proportion to applied pressure essentially independent of rotational speed or time variants.
Centrifugal compressors are also employed on some low volume OEM applications and aftermarket applications in a belt driven configuration. They create a very potent configuration in upper engine speed ranges but the inertia of the high speed impellers as reflected through their step up gearboxes to the drive pulley create exceedingly high loads on the belt upon rapid engine speed changes. They are also at the disadvantage that the pressure or boost created by the spinning impeller is a function of speed squared. Thus, it is a compromise as to the pulley ratio at which meaningful boost is created in the lower engine speed ranges without consuming huge amounts of power at high engine speeds.
U.S. Pat. No. 7,490,594 B2 teaches an elaborate mechanism in which a hydraulic motor is implemented either to provide or absorb power from a turbocharger shaft. The fixed displacement hydraulic motor is coupled to a variable pump/motor of piston and swash plate design which in turn is coupled to the engine such that energy can be effectively transferred in either direction. Given that the mechanism permanently couples the turbocharger shaft to the hydraulic drive, it would represent a large power loss in the operational region after the turbocharger is accelerated but before there is adequate power available to effectively transfer back to the engine. Further piston swash plate hydraulic devices are expensive devices and would limit the market appeal of such a system.
Unrelated to the field of force air induction for an internal combustion engine, U.S. Pat. No. 5,561,978 to Buschur and associated patents teach the use of two fixed displacement motors driving a common output shaft such that a pseudo variable displacement motor is produced.
U.S. Pat. No. 5,076,060 to Adeff teaches a control mechanism for a hydraulic assisted turbo which allows the driver to select a sport mode in which the hydraulics are activated. Upon subsequent mild use of the accelerator the hydraulics are de-activated after a period of time to reduce power consumption.
U.S. Pat. No. 4,729,225 to Bucher teaches a turbocharger energy recovery system in which a variable motor/pump coupled to the turbocharger shaft is utilized to either accelerate the turbocharger shaft through means of hydraulic flow generated by a pump powered in turn by an electric motor. Or, recover energy from the turbocharger shaft and turn a fixed displacement motor to drive auxiliary loads.
U.S. Pat. No. 4,083,188 to Kumm teaches a turbocharger coupled to a hydraulic motor/pump in fluid communication with a pump geared to the engine to maintain desired pressure differentials between engine intake and exhaust manifolds. An accumulator is employed to allow pressurized fluid to turn the pump coupled to the engine thus defining an alternate engine starting device.
The above-referenced patents typify the state of the art. Presently, vehicle manufacturers are downsizing internal combustion engines (Otto and Diesel cycle types) to meet fuel economy and emissions regulations. Forced air induction, typically accomplished through turbocharging, is becoming prevalent through-out the ground transportation (passenger vehicles and trucks) industry to maintain or even improve current levels of overall vehicle performance. Costs driven by emissions issues and lag reduction strategies place such turbo systems out of economic reach of low end standard equipment vehicles.
Commercial hydraulic hardware is typically too expensive and heavy for automotive use. Turbo systems often intrude on power-train emissions. The higher thermal mass and restriction of turbo equipped exhaust systems drive expensive add-ons to avoid retarding the light off of the catalytic converter. Solutions to reduce “turbo lag” such as sequential and variable designs raise costs and complexity while exacerbating these emissions issues. Superchargers provide the “off the line” torque drivers desire. Traditional belt driven superchargers provide the best “replacement for displacement”, but are expensive, cumbersome to implement and take power pumping air even when not needed.
The basic hydraulic circuit and drive mechanism as defined in the above identified priority application are still applicable.
It is, therefore, a primary object of the present invention to re-deploy existing automotive radiator fan drive technology to provide a cost effective and easily implemented forced air induction solution suitable for low end standard equipment vehicles which simultaneously improves fuel economy and vehicle performance. The present invention provides components designed to be competitive in the “no frills” automotive radiator fan marketplace.